Alumina Coated Metal Wool as a Particulate Filter for Diesel Powered Vehicles

Filters which employ alumina-coated steel wool as the matrix offer a promising means for removing soot particles from diesel exhaust. The performance of diesel exhaust filters (DEF’s), which consist of two alumina coated stainless-steel-wool filled cartridges inserted into an outer housing, will be discussed. In this type of filter, the collection efficiency and backpressure are determined by the metal wool packing density, alumina coating thickness and the physical dimensions of the filter.

Combustion of the trapped soot is the most feasible method for regenerating the DEF. A catalytic torch has thus been employed to heat exhaust to temperatures required for regeneration. With this torch in line with the DEF, hydrocarbons injected into the exhaust are catalytically oxidized and the exothermic heat used to heat the exhaust. A catalytic torch has been used to regenerate filters many times at 150 to 200 mile intervals during durability tests.